1. Field of the Invention
This invention relates to a blended yarn useful for the production of fabrics that possess the combination of improved comfort, due to its high moisture regain, and superior arc protection. This invention also relates to garments produced with such fabrics.
2. Description of Related Art
U.S. Pat. No. 7,348,059 to Zhu et al. discloses modacrylic/aramid fiber blends for use in arc and flame protective fabrics and garments. Such blends have on average a high content (40-70 weight percent) modacrylic fiber and lower content (10 to 40 weight percent) meta-aramid fiber having a degree of crystallinity of at least 20%, and para-aramid fiber (5 to 20 weight percent). Fabrics and garments made from such blends provide protection from electrical arcs and exposures to flash fires up to 3 seconds.
United States Patent Application Publication US2005/0025963 to Zhu discloses a fire retardant blend, yarn, fabric and article of clothing made from a blend of 10-75 parts of at least one aramid staple fiber, 15 to 80 parts by weight of at least one modacrylic staple fiber, and 5 to 30 parts by weight of at least one aliphatic polyamide staple fiber. This blend will not provide a Category 2 arc rating for fabrics in the range of 186.5 to 237 grams per square meter (5.5 to 7 ounces per square yard) because of the high proportion of flammable aliphatic polyamide fiber in this blend.
U.S. Pat. No. 7,156,883 to Lovasic et al. discloses a fiber blend, fabrics, and protective garments comprising amorphous meta-aramid fiber, crystallized meta-aramid fiber, and flame retardant cellulosic fiber, the meta-aramid fiber being 50 to 85 weight percent with one to two thirds of the meta-aramid fiber being amorphous and with two to one third of the meta-aramid fiber being crystalline. Again, fabrics made by these blends would not provide a Category 2 arc rating for fabrics in the range of 186.5 to 237 grams per square meter (5.5 to 7 ounces per square yard).
United States Patent Application Publication US2010/0299816 to Zhu discloses crystallized meta-aramid blends for improved flash fire protection and superior arc protection. consisting essentially of from (a) 50 to 60 weight percent meta-aramid fiber having a degree of crystallinity of at least 20%, (b) 31 to 39 weight percent modacrylic fiber, and (c) 5 to 15 weight percent para-aramid fiber, based on the total weight of components (a), (b), and (c). In some embodiments, 1 to 3 weight percent of the meta-aramid fiber is replaced with antistatic fiber with the proviso that at least 50 weight percent meta-aramid fiber is maintained. The garments provide thermal protection such that a wearer would experience less than a 65 percent predicted body burn when exposed to a flash fire exposure of 4 seconds per ASTM F1930, while maintaining a Category 2 arc rating per ASTM F1959 and NFPA 70E. The basis weight of fabrics that have both the desired arc and flash fire performance is 135 g/m2 (4 oz/yd2) or greater.
U.S. Pat. No. 7,744,999 to Zhu relates to yarn for use in arc and flame protection, and fabrics and garments made from that yarn, the yarn consisting essentially of from (a) 50 to 80 weight percent meta-aramid fiber having a degree of crystallinity of at least 20%, (b) 10 to 30 weight percent modacrylic fiber, (c) 5 to 20 weight percent para-aramid fiber, and (d) 1 to 3 weight percent antistatic fiber based on the total weight of components (a), (b), (c) and (d). The fabrics and garments have a basis weight in the range of 186.5 to 237 grams per square meter (5.5 to 7 ounces per square yard). In one embodiment, garments made from the yarn provide thermal protection such that a wearer would experience less than a 65 percent predicted body burn when exposed to a flash fire exposure of 4 seconds per ASTM F1930, while maintaining a Category 2 arc rating.
Unfortunately, the aforementioned fabrics that provide best protection tend to have lower moisture regain and therefore can be relatively uncomfortable in some environments. Apparel designed to protect an individual from electrical arcs is of use only if it is worn by the individual in a hazardous environments. If the apparel is uncomfortable, an individual is more likely to forego the protective apparel, risking injury. Therefore any improvement in the comfort of arc protective garments is welcomed.